Mahle 80mm piston set

[Porttuning.com]

Hello Guys, these pistons are brand new, and they are for the 1588cc VW engine. If any one is interested, I'm asking $175.00 for them. They come with rings, pins, and clips.

Thank you
Jose Rotger
www.porttuning.com

[Bill Miller]

What compression ratio are they?

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MARRS #25 ITB Rabbit GTI
SCCA 279608

[Porttuning.com]

Hello Bill, these are for the EJ 1588cc engine which came with 79.5mm pistons and 8.0:1 compression. These are 1st over stock replacments.

Thank you,
Jose Rotger
www.porttuning.com

[Bill Miller]

Thanks for the info Jose, I was looking for some 10:1 or 11:1 ones.

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MARRS #25 ITB Rabbit GTI
SCCA 279608

[marker]

Bill, I have a very neat way of making higher compression 1.6L or even 1.7L pistons.

As you are probably aware, the 1.5(short stroke), 1.6L, and 1.7L engines all shared a common block, as well as rods, and bore. When VW went from 1.5 to 1.6 and then to 1.7 litres, they changed the stroke, and the piston pin height to keep the compression low. So, if you were to drop in a 1.5L piston onto a 1.6L crank, you would end up with a piston that was sticking up above the deck surface. One would then machine the crown of the piston, to lower the compression ratio. You would lose a bit of the squench area of the piston, but the gains from the compression are huge, as you probably know.

When I made my 1.5L pistons into higher compression 1.6L pistons, I removed material off of the crown, but it still left a TINY amount of the dish in the center of the piston. To figure out exactly how much, I think you will have to do some experimenting. It might take you a few visits back and forth to your (newly found friendly) machinist, but it will be well worth it. I revved mine well past 6500 RPM, with no ill effects. There is plenty of material available to machine away, so no reliability issues ever came up.

I also had a neat way of getting a big intake valve into the 1.5/1.6/1.7L head, and if you are curious, we can talk more.

Hope this helps.

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Pete Mills

[racer14itc]

This is a very common "trick" and I bet more than a few ITC VW's have had this "improvement" done to them.

Obviously it's not legal for ITC but a cheap way to get higher compression pistons for an limited prep engine for example.

Two things to be careful of when doing this modification:

1. Remember that the ring package will now be higher, so if you're putting this into an existing block make sure you remove any ridge at the top of the bore or you're likely to crack the top compression ring.

2. The machining of the top of the piston also effectively moves the top compression ring closer to the piston deck, which can lead to higher operating temperatures and warp the top compression ring land, resulting in a top compression ring failure. This obviously depends on the final compression ratio, advance, mixture, etc.

Just a couple of things to think about!

MC

[Bill Miller]

Pete and Mark,

I'm aware of this 'trick'. Similar to using 16v pistons in a 1.8 8v to get higher compression. I've never had a set done, but I'm curious as to what it usually costs to have a set done. The other question, is what's the current availability of 1.5 liter pistons in 80.0mm and 80.5mm? With the machine work and all, I would wonder if they'd be any cheaper than custom, forged (not even gonna go there) pistons. And, you wouldn't have the issue w/ the upper ring.

Thanks for the info guys!

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MARRS #25 ITB Rabbit GTI
SCCA 279608

[racer_tim]

Bill, that's what I did on my Limited Prep 1.8 GP motor. Had my local machine shop match the deck height on my 16v 1.8 pistons (Got on eBay) to the 8v 1.8 piston. That, and along with prepping/balancing the stock rods, and installing ARP bolts was around $425.



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Tim Linerud
San Francisco Region SCCA
#95 LP GP Wabbit
http://linerud.myvnc.com/racing/index.html

[Porttuning.com]

Hello Bill, about 15 years go when I needed a new engine in my 75 Autocross Rabbit. I built the 1.6 engine using the piston from the 1.5. It worked great. The piston set was pretty cheap, and the machine shop only charged me $40.00 to cut 0.040" of the top. However, I'm not sure if these pistons are still available, but I will check with my two sources tomorrow. If we can't fine the pistons and the only choice we have is to go with forged, I can have them made by Wiseco. The sets come complete, and the cheapest I can let them go for is $400 a set. We can make them to any spec you want. The down side it will take 4-5 weeks.

Thank you,
Jose Rotger
www.porttuning.com

[wvonkessler]

Tim:

What CR are you running in the motor? I'd like to do this with a 1.8 GTI engine being prepped for ClubRally, and would like to run about 11.5:1. Do you know how much I would have to mill to get that ratio?

Thanks,

Wilson

Originally posted by racer_tim:
Bill, that's what I did on my Limited Prep 1.8 GP motor. Had my local machine shop match the deck height on my 16v 1.8 pistons (Got on eBay) to the 8v 1.8 piston. That, and along with prepping/balancing the stock rods, and installing ARP bolts was around $425.

[racer_tim]

I can only run 11.0:1 in the Limited Prep GP.

I'm not actually sure, since I didn't do any analysis on CR.

P.S. Just spotted a 1.5 set of pistons on eBay.
http://cgi.ebay.com/ebaymotors/ws/eBayISAP...item=2408952381

Wilson, I'd have to look at the receipt as far has how much was actually taken off the top. It wasn't very much.



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Tim Linerud
San Francisco Region SCCA
#95 LP GP Wabbit
http://linerud.myvnc.com/racing/index.html